/**
 * @author aleeper / http://adamleeper.com/
 * @author mrdoob / http://mrdoob.com/
 * @author gero3 / https://github.com/gero3
 *
 * Description: A THREE loader for STL ASCII files, as created by Solidworks and other CAD programs.
 *
 * Supports both binary and ASCII encoded files, with automatic detection of type.
 *
 * Limitations:
 *  Binary decoding supports "Magics" color format (http://en.wikipedia.org/wiki/STL_(file_format)#Color_in_binary_STL).
 *  There is perhaps some question as to how valid it is to always assume little-endian-ness.
 *  ASCII decoding assumes file is UTF-8. Seems to work for the examples...
 *
 * Usage:
 *  var loader = new THREE.STLLoader();
 *  loader.load( './models/stl/slotted_disk.stl', function ( geometry ) {
 *    scene.add( new THREE.Mesh( geometry ) );
 *  });
 *
 * For binary STLs geometry might contain colors for vertices. To use it:
 *  // use the same code to load STL as above
 *  if (geometry.hasColors) {
 *    material = new THREE.MeshPhongMaterial({ opacity: geometry.alpha, vertexColors: THREE.VertexColors });
 *  } else { .... }
 *  var mesh = new THREE.Mesh( geometry, material );
 */


export function STLLoader(THREE) {
	
	THREE.STLLoader = function ( manager ) {

		this.manager = ( manager !== undefined ) ? manager : THREE.DefaultLoadingManager;

	};

	THREE.STLLoader.prototype = {

		constructor: THREE.STLLoader,

		load: function ( url, onLoad, onProgress, onError ) {

			var scope = this;

			var loader = new THREE.XHRLoader( scope.manager );
			loader.setResponseType( 'arraybuffer' );
			loader.load( url, function ( text ) {

				onLoad( scope.parse( text ) );

			}, onProgress, onError );

		},

		parse: function ( data ) {

			var isBinary = function () {

				var expect, face_size, n_faces, reader;
				reader = new DataView( binData );
				face_size = ( 32 / 8 * 3 ) + ( ( 32 / 8 * 3 ) * 3 ) + ( 16 / 8 );
				n_faces = reader.getUint32( 80, true );
				expect = 80 + ( 32 / 8 ) + ( n_faces * face_size );

				if ( expect === reader.byteLength ) {

					return true;

				}

				// some binary files will have different size from expected,
				// checking characters higher than ASCII to confirm is binary
				var fileLength = reader.byteLength;
				for ( var index = 0; index < fileLength; index ++ ) {

					if ( reader.getUint8( index, false ) > 127 ) {

						return true;

					}

				}

				return false;

			};

			var binData = this.ensureBinary( data );

			return isBinary()
				? this.parseBinary( binData )
				: this.parseASCII( this.ensureString( data ) );

		},

		parseBinary: function ( data ) {

			var reader = new DataView( data );
			var faces = reader.getUint32( 80, true );

			var r, g, b, hasColors = false, colors;
			var defaultR, defaultG, defaultB, alpha;

			// process STL header
			// check for default color in header ("COLOR=rgba" sequence).

			for ( var index = 0; index < 80 - 10; index ++ ) {

				if ( ( reader.getUint32( index, false ) == 0x434F4C4F /*COLO*/ ) &&
					( reader.getUint8( index + 4 ) == 0x52 /*'R'*/ ) &&
					( reader.getUint8( index + 5 ) == 0x3D /*'='*/ ) ) {

					hasColors = true;
					colors = new Float32Array( faces * 3 * 3 );

					defaultR = reader.getUint8( index + 6 ) / 255;
					defaultG = reader.getUint8( index + 7 ) / 255;
					defaultB = reader.getUint8( index + 8 ) / 255;
					alpha = reader.getUint8( index + 9 ) / 255;

				}

			}

			var dataOffset = 84;
			var faceLength = 12 * 4 + 2;

			var offset = 0;

			var geometry = new THREE.BufferGeometry();

			var vertices = new Float32Array( faces * 3 * 3 );
			var normals = new Float32Array( faces * 3 * 3 );

			for ( var face = 0; face < faces; face ++ ) {

				var start = dataOffset + face * faceLength;
				var normalX = reader.getFloat32( start, true );
				var normalY = reader.getFloat32( start + 4, true );
				var normalZ = reader.getFloat32( start + 8, true );

				if ( hasColors ) {

					var packedColor = reader.getUint16( start + 48, true );

					if ( ( packedColor & 0x8000 ) === 0 ) {

						// facet has its own unique color

						r = ( packedColor & 0x1F ) / 31;
						g = ( ( packedColor >> 5 ) & 0x1F ) / 31;
						b = ( ( packedColor >> 10 ) & 0x1F ) / 31;

					} else {

						r = defaultR;
						g = defaultG;
						b = defaultB;

					}

				}

				for ( var i = 1; i <= 3; i ++ ) {

					var vertexstart = start + i * 12;

					vertices[ offset ] = reader.getFloat32( vertexstart, true );
					vertices[ offset + 1 ] = reader.getFloat32( vertexstart + 4, true );
					vertices[ offset + 2 ] = reader.getFloat32( vertexstart + 8, true );

					normals[ offset ] = normalX;
					normals[ offset + 1 ] = normalY;
					normals[ offset + 2 ] = normalZ;

					if ( hasColors ) {

						colors[ offset ] = r;
						colors[ offset + 1 ] = g;
						colors[ offset + 2 ] = b;

					}

					offset += 3;

				}

			}

			geometry.addAttribute( 'position', new THREE.BufferAttribute( vertices, 3 ) );
			geometry.addAttribute( 'normal', new THREE.BufferAttribute( normals, 3 ) );

			if ( hasColors ) {

				geometry.addAttribute( 'color', new THREE.BufferAttribute( colors, 3 ) );
				geometry.hasColors = true;
				geometry.alpha = alpha;

			}

			return geometry;

		},

		parseASCII: function ( data ) {

			var geometry, length, normal, patternFace, patternNormal, patternVertex, result, text;
			geometry = new THREE.Geometry();
			patternFace = /facet([\s\S]*?)endfacet/g;

			while ( ( result = patternFace.exec( data ) ) !== null ) {

				text = result[ 0 ];
				patternNormal = /normal[\s]+([\-+]?[0-9]+\.?[0-9]*([eE][\-+]?[0-9]+)?)+[\s]+([\-+]?[0-9]*\.?[0-9]+([eE][\-+]?[0-9]+)?)+[\s]+([\-+]?[0-9]*\.?[0-9]+([eE][\-+]?[0-9]+)?)+/g;

				while ( ( result = patternNormal.exec( text ) ) !== null ) {

					normal = new THREE.Vector3( parseFloat( result[ 1 ] ), parseFloat( result[ 3 ] ), parseFloat( result[ 5 ] ) );

				}

				patternVertex = /vertex[\s]+([\-+]?[0-9]+\.?[0-9]*([eE][\-+]?[0-9]+)?)+[\s]+([\-+]?[0-9]*\.?[0-9]+([eE][\-+]?[0-9]+)?)+[\s]+([\-+]?[0-9]*\.?[0-9]+([eE][\-+]?[0-9]+)?)+/g;

				while ( ( result = patternVertex.exec( text ) ) !== null ) {

					geometry.vertices.push( new THREE.Vector3( parseFloat( result[ 1 ] ), parseFloat( result[ 3 ] ), parseFloat( result[ 5 ] ) ) );

				}

				length = geometry.vertices.length;

				geometry.faces.push( new THREE.Face3( length - 3, length - 2, length - 1, normal ) );

			}

			geometry.computeBoundingBox();
			geometry.computeBoundingSphere();

			return geometry;

		},

		ensureString: function ( buf ) {

			if ( typeof buf !== "string" ) {

				var array_buffer = new Uint8Array( buf );
				var str = '';
				for ( var i = 0; i < buf.byteLength; i ++ ) {

					str += String.fromCharCode( array_buffer[ i ] ); // implicitly assumes little-endian

				}
				return str;

			} else {

				return buf;

			}

		},

		ensureBinary: function ( buf ) {

			if ( typeof buf === "string" ) {

				var array_buffer = new Uint8Array( buf.length );
				for ( var i = 0; i < buf.length; i ++ ) {

					array_buffer[ i ] = buf.charCodeAt( i ) & 0xff; // implicitly assumes little-endian

				}
				return array_buffer.buffer || array_buffer;

			} else {

				return buf;

			}

		}

	};

	if ( typeof DataView === 'undefined' ) {

		DataView = function( buffer, byteOffset, byteLength ) {

			this.buffer = buffer;
			this.byteOffset = byteOffset || 0;
			this.byteLength = byteLength || buffer.byteLength || buffer.length;
			this._isString = typeof buffer === "string";

		};

		DataView.prototype = {

			_getCharCodes: function( buffer, start, length ) {

				start = start || 0;
				length = length || buffer.length;
				var end = start + length;
				var codes = [];
				for ( var i = start; i < end; i ++ ) {

					codes.push( buffer.charCodeAt( i ) & 0xff );

				}
				return codes;

			},

			_getBytes: function ( length, byteOffset, littleEndian ) {

				var result;

				// Handle the lack of endianness
				if ( littleEndian === undefined ) {

					littleEndian = this._littleEndian;

				}

				// Handle the lack of byteOffset
				if ( byteOffset === undefined ) {

					byteOffset = this.byteOffset;

				} else {

					byteOffset = this.byteOffset + byteOffset;

				}

				if ( length === undefined ) {

					length = this.byteLength - byteOffset;

				}

				// Error Checking
				if ( typeof byteOffset !== 'number' ) {

					throw new TypeError( 'DataView byteOffset is not a number' );

				}

				if ( length < 0 || byteOffset + length > this.byteLength ) {

					throw new Error( 'DataView length or (byteOffset+length) value is out of bounds' );

				}

				if ( this.isString ) {

					result = this._getCharCodes( this.buffer, byteOffset, byteOffset + length );

				} else {

					result = this.buffer.slice( byteOffset, byteOffset + length );

				}

				if ( ! littleEndian && length > 1 ) {

					if ( Array.isArray( result ) === false ) {

						result = Array.prototype.slice.call( result );

					}

					result.reverse();

				}

				return result;

			},

			// Compatibility functions on a String Buffer

			getFloat64: function ( byteOffset, littleEndian ) {

				var b = this._getBytes( 8, byteOffset, littleEndian ),

					sign = 1 - ( 2 * ( b[ 7 ] >> 7 ) ),
					exponent = ( ( ( ( b[ 7 ] << 1 ) & 0xff ) << 3 ) | ( b[ 6 ] >> 4 ) ) - ( ( 1 << 10 ) - 1 ),

				// Binary operators such as | and << operate on 32 bit values, using + and Math.pow(2) instead
					mantissa = ( ( b[ 6 ] & 0x0f ) * Math.pow( 2, 48 ) ) + ( b[ 5 ] * Math.pow( 2, 40 ) ) + ( b[ 4 ] * Math.pow( 2, 32 ) ) +
								( b[ 3 ] * Math.pow( 2, 24 ) ) + ( b[ 2 ] * Math.pow( 2, 16 ) ) + ( b[ 1 ] * Math.pow( 2, 8 ) ) + b[ 0 ];

				if ( exponent === 1024 ) {

					if ( mantissa !== 0 ) {

						return NaN;

					} else {

						return sign * Infinity;

					}

				}

				if ( exponent === - 1023 ) {

					// Denormalized
					return sign * mantissa * Math.pow( 2, - 1022 - 52 );

				}

				return sign * ( 1 + mantissa * Math.pow( 2, - 52 ) ) * Math.pow( 2, exponent );

			},

			getFloat32: function ( byteOffset, littleEndian ) {

				var b = this._getBytes( 4, byteOffset, littleEndian ),

					sign = 1 - ( 2 * ( b[ 3 ] >> 7 ) ),
					exponent = ( ( ( b[ 3 ] << 1 ) & 0xff ) | ( b[ 2 ] >> 7 ) ) - 127,
					mantissa = ( ( b[ 2 ] & 0x7f ) << 16 ) | ( b[ 1 ] << 8 ) | b[ 0 ];

				if ( exponent === 128 ) {

					if ( mantissa !== 0 ) {

						return NaN;

					} else {

						return sign * Infinity;

					}

				}

				if ( exponent === - 127 ) {

					// Denormalized
					return sign * mantissa * Math.pow( 2, - 126 - 23 );

				}

				return sign * ( 1 + mantissa * Math.pow( 2, - 23 ) ) * Math.pow( 2, exponent );

			},

			getInt32: function ( byteOffset, littleEndian ) {

				var b = this._getBytes( 4, byteOffset, littleEndian );
				return ( b[ 3 ] << 24 ) | ( b[ 2 ] << 16 ) | ( b[ 1 ] << 8 ) | b[ 0 ];

			},

			getUint32: function ( byteOffset, littleEndian ) {

				return this.getInt32( byteOffset, littleEndian ) >>> 0;

			},

			getInt16: function ( byteOffset, littleEndian ) {

				return ( this.getUint16( byteOffset, littleEndian ) << 16 ) >> 16;

			},

			getUint16: function ( byteOffset, littleEndian ) {

				var b = this._getBytes( 2, byteOffset, littleEndian );
				return ( b[ 1 ] << 8 ) | b[ 0 ];

			},

			getInt8: function ( byteOffset ) {

				return ( this.getUint8( byteOffset ) << 24 ) >> 24;

			},

			getUint8: function ( byteOffset ) {

				return this._getBytes( 1, byteOffset )[ 0 ];

			}

		 };

	}
}